Neonatal death after hypoxic ischaemic encephalopathy: does a postmortem add to the final diagnoses?

A Controversial Medicolegal Issue: Timing the Onset of Perinatal Hypoxic-Ischemic Brain Injury

Perinatal hypoxic-ischemic brain injury, as a result of chronic, subacute, and acute insults, represents the pathological consequence of fetal distress and birth or perinatal asphyxia, that is, “nonreassuring fetal status.” Hypoxic-ischemic injury (HII) is typically characterized by an early phase of damage, followed by a delayed inflammatory local response, in an apoptosis-necrosis continuum. In the early phase, the cytotoxic edema and eventual acute lysis take place; with reperfusion, additional damage should be assigned to excitotoxicity and oxidative stress. Finally, a later phase involves all the inflammatory activity and long-term neural tissue repairing and remodeling. In this model mechanism, loss of mitochondrial function is supposed to be the hallmark of secondary injury progression, and autophagy which is lysosome-mediated play a role in enhancing brain injury. Early-induced molecules driven by hypoxia, as chaperonins HSPs and ORP150, besides common markers for inflammatory responses, have predictive value in timing the onset of neonatal HII; on the other hand, clinical biomarkers for HII diagnosis, as CK-BB, LDH, S-100beta, and NSE, could be useful to predict outcomes.

Neuronal cell death in neonatal hypoxia-ischemia

Perinatal hypoxic-ischemic encephalopathy (HIE) is a significant cause of mortality and morbidity in infants and young children. Therapeutic opportunities are very limited for neonatal and pediatric HIE. Specific neural systems and populations of cells are selectively vulnerable in HIE; however, the mechanisms of degeneration are unresolved. These mechanisms involve oxidative stress, excitotoxicity, inflammation, and the activation of several different cell death pathways. Decades ago the structural and mechanistic basis of the cellular degeneration in HIE was thought to be necrosis. Subsequently, largely due to advances in cell biology and to experimental animal studies, emphasis has been switched to apoptosis or autophagy mediated by programmed cell death (PCD) mechanisms as important forms of degeneration in HIE. We have conceptualized based on morphological and biochemical data that this degeneration is better classified according to an apoptosis-necrosis cell death continuum and that programmed cell necrosis has prominent contribution in the neurodegeneration of HIE in animal models. It is likely that neonatal HIE evolves through many cell death chreodes influenced by the dynamic injury landscape. The relevant injury mechanisms remain to be determined in human neonatal HIE, though preliminary work suggests a complexity in the cell death mechanisms greater than that anticipated from experimental animal models. The accurate identification of the various cell death chreodes and their mechanisms unfolding within the immature brain matrix could provide fresh insight for developing meaningful therapies for neonatal and pediatric HIE.

Room air resuscitation of the depressed newborn: A systematic review and meta-analysis

Understanding of the potential dangers of hyperoxia in the newborn is growing. Several studies have examined the use of room air for the resuscitation of newborns.

OBJECTIVE

To assess the effects of room air resuscitation versus 100% oxygen resuscitation on mortality at 1 week and 1 month in asphyxiated newborn infants.

STUDY DESIGN

Systematic review and meta-analysis of seven randomized and quasi-randomised controlled trials comparing room air and 100% oxygen resuscitation of newborn infants.

RESULTS

Compared to the 100% oxygen resuscitation group, neonates in the room air resuscitation group had a lower mortality both in the first week of life (odds ratio 0.70, 95% CI 0.50, 0.98) and at 1 month and beyond (odds ratio 0.63, 95% CI 0.42, 0.94). The incidence of severe hypoxic ischemic encephalopathy (Stage II and Stage III) was similar between the two groups.

CONCLUSION

This meta-analysis supports the hypothesis that room air is superior to 100% oxygen as the initial choice for resuscitating clinically depressed newborns as it may result in a lower mortality rate. However, adequately powered studies of long-term neurodevelopmental outcomes are not yet available.